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Dive into the research topics where Andrew J. McLachlan is active.

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Featured researches published by Andrew J. McLachlan.


Journal of Clinical Epidemiology | 2012

Polypharmacy cutoff and outcomes: five or more medicines were used to identify community-dwelling older men at risk of different adverse outcomes

Danijela Gnjidic; Sarah N. Hilmer; Fiona M. Blyth; Vasi Naganathan; Louise M. Waite; Markus J. Seibel; Andrew J. McLachlan; Robert G. Cumming; David J. Handelsman; David G. Le Couteur

OBJECTIVE This study aimed to determine an optimal discriminating number of concomitant medications associated with geriatric syndromes, functional outcomes, and mortality in community-dwelling older men. STUDY DESIGN AND SETTING Older men aged ≥ 70 years (n=1,705), enrolled in the Concord Health and Aging in Men Project were studied. Receiver operating characteristic curve analysis using the Youden Index and the area under the curve was performed to determine discriminating number of medications in relation to each outcome. RESULTS The highest value of the Youden Index for frailty was obtained for a cutoff point of 6.5 medications compared with a cutoff of 5.5 for disability and 3.5 for cognitive impairment. For mortality and incident falls, the highest value of Youden Index was obtained for a cutoff of 4.5 medications. For every one increase in number of medications, the adjusted odds ratios were 1.13 (95% confidence interval [CI]=1.06-1.21) for frailty, 1.08 (95% CI=1.00-1.15) for disability, 1.09 (95% CI=1.04-1.15) for mortality, and 1.07 (95% CI=1.03-1.12) for incident falls. There was no association between increasing number of medications and cognitive impairment. CONCLUSION The study supports the use of five or more medications in the current definition of polypharmacy to estimate the medication-related adverse effects for frailty, disability, mortality, and falls.


Clinical Pharmacokinectics | 2000

Clinical pharmacokinetics and pharmacodynamics of celecoxib : A selective cyclo-oxygenase-2 inhibitor

Neal M. Davies; Andrew J. McLachlan; Ric Day; Kenneth M. Williams

Celecoxib, a nonsteroidal anti-inflammatory drug (NSAID), is the first specific inhibitor of cyclo-oxygenase-2 (COX-2) approved to treat patients with rheumatism and osteoarthritis. Preliminary data suggest that celecoxib also has analgesic and anticancer properties. The selective inhibition of COX-2 is thought to lead to a reduction in the unwanted effects of NSAIDs. Upper gastrointestinal complication rates in clinical trials are significantly lower for celecoxib than for traditional nonselective NSAIDs (e.g. naproxen, ibuprofen and diclofenac).The rate of absorption of celexocib is moderate when given orally (peak plasma drug concentration occurs after 2 to 4 hours), although the extent of absorption is not known. Celexocib is extensively protein bound, primarily to plasma albumin, and has an apparent volume of distribution of 455 ± 166L in humans. The area under the plasma concentration-time curve (AUC) of celecoxib increases in proportion to increasing oral doses between 100 and 800mg. Celecoxib is eliminated following biotransformation to carboxylic acid and glucuronide metabolites that are excreted in urine and faeces, with little drug (2%) being eliminated unchanged in the urine. Celecoxib is metabolised primarily by the cytochrome P450 (CYP) 2C9 isoenzyme and has an elimination half-life of about 11 hours in healthy individuals. Racial differences in drug disposition and pharmacokinetic changes in the elderly have been reported for celecoxib.Plasma concentrations (AUC) of celecoxib appear to be 43% lower in patients with chronic renal insufficiency [glomerular filtration rate 2.1 to 3.6 L/h (35 to 60 ml/min)] compared with individuals with healthy renal function, with a 47% increase in apparent clearance. Compared with healthy controls, it has been reported that the steady-state AUC is increased by approximately 40% and 180% in patients with mild and moderate hepatic impairment, respectively.Celecoxib does not appear to interact with warfarin, ketoconazole or methotrexate; however, clinically significant drug interactions with fluconazole and lithium have been documented. As celecoxib is metabolised by CYP2C9, increased clinical vigilance is required during the coadministration of other substrates or inhibitors of this enzyme.


Fundamental & Clinical Pharmacology | 2007

Clinical pharmacology in the geriatric patient

Sarah N. Hilmer; Andrew J. McLachlan; David G. Le Couteur

Geriatric patients are a subset of older people with multiple comorbidities that usually have significant functional implications. Geriatric patients have impaired homeostasis and wide inter‐individual variability. Comprehensive geriatric assessment captures the complexity of the problems that characterize frail older patients and can be used to guide management, including prescribing. Prescribing for geriatric patients requires an understanding of the efficacy of the medication in frail older people, assessment of the risk of adverse drug events, discussion of the harm:benefit ratio with the patient, a decision about the dose regime and careful monitoring of the patients response. This requires evaluation of evidence from clinical trials, application of the evidence to frail older people through an understanding of changes in pharmacokinetics and pharmacodynamics, and attention to medication management issues. Given that most disease occurs in older people, and that older people are the major recipients of drug therapy in the Western world, increased research and a better evidence base is essential to guide clinicians who manage geriatric patients.


Drugs & Aging | 2008

Medication Withdrawal Trials in People Aged 65 Years and Older A Systematic Review

Shoba Iyer; Vasi Naganathan; Andrew J. McLachlan; David G. Le Conteur

The objective of this review was to assess the benefits and risks of medication withdrawal in older people as documented in published trials of medication withdrawal. This was done by systematic review of the evidence from clinical trials of withdrawal of specific classes of medications in patient populations with a mean age of ≥65 years. We identified all relevant articles published between 1966 and 2007 initially through electronic searches on PubMed and manual searches of review articles. Numerous search terms related to the withdrawal of medication in older people were utilized. Clinical trials identified were reviewed according to predetermined inclusion/exclusion criteria. Only trials that focused on the withdrawal of specific classes of medication were included. Thirty-one published studies (n = 8972 subjects) met the inclusion criteria, including four randomized and placebo-controlled studies (n = 448 subjects) of diuretic withdrawal, nine open-label and prospective observational studies (n = 7188 subjects) of withdrawal of antihypertensives (including diuretics), 16 studies (n = 1184 patients) of withdrawal of sedative, antidepressant, cholinesterase inhibitor and antipsychotic medications, and 1 study each of withdrawal of nitrates and digoxin. These studies were of heterogeneous study design, patient selection criteria and follow-up. Withdrawal of diuretics was maintained in 51–100% of subjects and was unsuccessful primarily when heart failure was present. Adverse effects from medication withdrawal were infrequently encountered. After withdrawal of antihypertensive therapy, many subjects (20–85%) remained normotensive or did not require reinstatement of therapy for between 6 months and 5 years, and there was no increase in mortality. Withdrawal of psychotropic medications was associated with a reduction in falls and improved cognition. In conclusion, there is some clinical trial evidence for the short-term effectiveness and/or lack of significant harm when medication withdrawal is undertaken for antihypertensive, benzodiazepine and psychotropic agents in older people.


BMJ | 2015

Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials.

Gustavo C Machado; Christopher G. Maher; Paulo H. Ferreira; Marina B. Pinheiro; Chung-Wei Christine Lin; Richard O. Day; Andrew J. McLachlan; Manuela L. Ferreira

Objective To investigate the efficacy and safety of paracetamol (acetaminophen) in the management of spinal pain and osteoarthritis of the hip or knee. Design Systematic review and meta-analysis. Data sources Medline, Embase, AMED, CINAHL, Web of Science, LILACS, International Pharmaceutical Abstracts, and Cochrane Central Register of Controlled Trials from inception to December 2014. Eligibility criteria for selecting studies Randomised controlled trials comparing the efficacy and safety of paracetamol with placebo for spinal pain (neck or low back pain) and osteoarthritis of the hip or knee. Data extraction Two independent reviewers extracted data on pain, disability, and quality of life. Secondary outcomes were adverse effects, patient adherence, and use of rescue medication. Pain and disability scores were converted to a scale of 0 (no pain or disability) to 100 (worst possible pain or disability). We calculated weighted mean differences or risk ratios and 95% confidence intervals using a random effects model. The Cochrane Collaboration’s tool was used for assessing risk of bias, and the GRADE approach was used to evaluate the quality of evidence and summarise conclusions. Results 12 reports (13 randomised trials) were included. There was “high quality” evidence that paracetamol is ineffective for reducing pain intensity (weighted mean difference −0.5, 95% confidence interval −2.9 to 1.9) and disability (0.4, −1.7 to 2.5) or improving quality of life (0.4, −0.9 to 1.7) in the short term in people with low back pain. For hip or knee osteoarthritis there was “high quality” evidence that paracetamol provides a significant, although not clinically important, effect on pain (−3.7, −5.5 to −1.9) and disability (−2.9, −4.9 to −0.9) in the short term. The number of patients reporting any adverse event (risk ratio 1.0, 95% confidence interval 0.9 to 1.1), any serious adverse event (1.2, 0.7 to 2.1), or withdrawn from the study because of adverse events (1.2, 0.9 to 1.5) was similar in the paracetamol and placebo groups. Patient adherence to treatment (1.0, 0.9 to 1.1) and use of rescue medication (0.7, 0.4 to 1.3) was also similar between groups. “High quality” evidence showed that patients taking paracetamol are nearly four times more likely to have abnormal results on liver function tests (3.8, 1.9 to 7.4), but the clinical importance of this effect is uncertain. Conclusions Paracetamol is ineffective in the treatment of low back pain and provides minimal short term benefit for people with osteoarthritis. These results support the reconsideration of recommendations to use paracetamol for patients with low back pain and osteoarthritis of the hip or knee in clinical practice guidelines. Systematic review registration PROSPERO registration number CRD42013006367.


Thrombosis and Haemostasis | 2014

Feasibility and cost-effectiveness of stroke prevention through community screening for atrial fibrillation using iPhone ECG in pharmacies: The SEARCH-AF study

Nicole Lowres; Lis Neubeck; Glenn Salkeld; Ines Krass; Andrew J. McLachlan; Julie Redfern; Alexandra A Bennett; Tom Briffa; Adrian Bauman; Carlos Martinez; Christopher Wallenhorst; J. Lau; David Brieger; Raymond W. Sy; S. B. Freedman

Atrial fibrillation (AF) causes a third of all strokes, but often goes undetected before stroke. Identification of unknown AF in the community and subsequent anti-thrombotic treatment could reduce stroke burden. We investigated community screening for unknown AF using an iPhone electrocardiogram (iECG) in pharmacies, and determined the cost-effectiveness of this strategy.Pharmacists performedpulse palpation and iECG recordings, with cardiologist iECG over-reading. General practitioner review/12-lead ECG was facilitated for suspected new AF. An automated AF algorithm was retrospectively applied to collected iECGs. Cost-effectiveness analysis incorporated costs of iECG screening, and treatment/outcome data from a United Kingdom cohort of 5,555 patients with incidentally detected asymptomatic AF. A total of 1,000 pharmacy customers aged ≥65 years (mean 76 ± 7 years; 44% male) were screened. Newly identified AF was found in 1.5% (95% CI, 0.8-2.5%); mean age 79 ± 6 years; all had CHA2DS2-VASc score ≥2. AF prevalence was 6.7% (67/1,000). The automated iECG algorithm showed 98.5% (CI, 92-100%) sensitivity for AF detection and 91.4% (CI, 89-93%) specificity. The incremental cost-effectiveness ratio of extending iECG screening into the community, based on 55% warfarin prescription adherence, would be


The Lancet | 2007

Assessment of diclofenac or spinal manipulative therapy, or both, in addition to recommended first-line treatment for acute low back pain: a randomised controlled trial

Mark J. Hancock; Christopher G. Maher; Jane Latimer; Andrew J. McLachlan; Chris Cooper; Richard O. Day; Megan F Spindler; James H. McAuley

AUD5,988 (€3,142;


Annals of Internal Medicine | 2012

Epidural Corticosteroid Injections in the Management of Sciatica: A Systematic Review and Meta-analysis

Rafael Z. Pinto; Christopher G. Maher; Manuela L. Ferreira; Mark J. Hancock; Vinicius C. Oliveira; Andrew J. McLachlan; Bart W. Koes; Paulo H. Ferreira

USD4,066) per Quality Adjusted Life Year gained and


Antimicrobial Agents and Chemotherapy | 2012

Multicenter Study of Voriconazole Pharmacokinetics and Therapeutic Drug Monitoring

Michael J. Dolton; John E. Ray; Sharon C.-A. Chen; Kingsley Ng; Lisa Pont; Andrew J. McLachlan

AUD30,481 (€15,993;


Clinical Pharmacology & Therapeutics | 2012

High‐Risk Prescribing and Incidence of Frailty Among Older Community‐Dwelling Men

Donijela Gnjidic; Sarah N. Hilmer; Fiona M. Blyth; V. Naganathan; Robert G. Cumming; David J. Handelsman; Andrew J. McLachlan; Darrell R. Abernethy; Emily Banks; D. G. Le Couteur

USD20,695) for preventing one stroke. Sensitivity analysis indicated cost-effectiveness improved with increased treatment adherence.Screening with iECG in pharmacies with an automated algorithm is both feasible and cost-effective. The high and largely preventable stroke/thromboembolism risk of those with newly identified AF highlights the likely benefits of community AF screening. Guideline recommendation of community iECG AF screening should be considered.

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Richard O. Day

St. Vincent's Health System

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Sarah N. Hilmer

Kolling Institute of Medical Research

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Jane Latimer

The George Institute for Global Health

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Susan E. Tett

University of Queensland

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